1. Field of the Invention
The present invention relates to protective coatings for furniture and combination cleaner protective coatings for furniture.
2. Background of the Art
Protective coatings for wood furniture surfaces and the like are designed to protect the underlying surface by filling the crevices and pores therein. These vary from permanent coatings requiring spraying, or brush applications such as shellac, nitrocellulose lacquers, varnish, or polyurethanes to temporary coatings comprising various oils and waxes. The latter usually consist of blends of mineral, vegetable, silicone and/or essential oils and small amounts of waxes. While these oils are easy to apply, they often tend to leave a greasy film and they, like the permanent coatings, do not provide much protection against water and alcohol spotting.
It is desirable for a furniture polish to aid in cleaning and protecting the furniture finish from such common damaging effects as finger marking, food and drink stains, and other surface deposits. They must be easy to apply, to spread, and to buff to a shine, and any excess must be easily removed.
As is known in the literature and the patent art, acrylate polymers are useful in providing protective coatings for flooring substrates where the coating must be able to form a tough film to protect the floor from wear and damage. In addition, polymers have been used in furniture polishes. Two characteristics useful in defining these polymers are their glass transition temperature (T.sub.g) and their solubility parameters (.delta.). Glass temperature is defined as the temperature at which an amorphous material (such as glass or a high molecular weight polymer) changes from a brittle vitreous state to a plastic state. Solubility parameter, .delta., is the square root of the cohesive-energy density, CED, which is the amount of energy required to vaporize one cubic centimeter of the hypothesized liquid. The latter is represented thermodynamically as follows ##EQU1## where E is the molar energy of vaporization, H is the heat of vaporization per mole, V is the molecular volume, R is the gas constant, and T is temperature.
The solubility parameter, .delta., of a solvent is a readily calculable quantity. The solubility parameter of a polymer (or for that matter of any non-volatile substance) cannot be determined directly because most polymers cannot be vaporized without decomposition. The solubility parameter of a polymer is therefore defined as the same as that of a solvent in which the polymer will mix (a) in all proportions, (b) without heat change, (c) without volume change and (d) without reaction or special association. (H. Burrell in J. Brandrup and E. H. Immergut, Ed. Polymer Handbook, 2nd ed., Interscience, N.Y., 1975, vol. IV, page 337).
The solubility of a given polymer in various solvents is largely determined by its chemical structure. As a general rule, structural similarity favors solubility; this means that the solubility of a given polymer in a given solvent is favored if the solubility parameters of polymer and solvent are equal or differ by no more than about .+-.1.5 (cal/cc)1/2. (van Krevelen, D. W., Properties of Polymers: Their estimation and Correlation with Chemical Structure, Elsevier Scientific Publishing Co., Amsterdam, 1976, page 129).
Solubility parameters are commonly used in polymer science to show solvent classes in which a particular polymer is soluble and is shown on a Solvent Strength Chart such as "Hydrogen Bonding Numbers and Solubility Parameters for Solvents", D. W. von Krevele, Properties of Polymers, Their Estimation and Correlation With Chemical Structure, 1976, pp. 582-584, graph p. 145. Solubility parameters are plotted on the X axis and hydrogen bonding character is plotted on the Y axis. As the solubility parameter increases from 7 to 12, the solvent's character changes from non-polar to polar in nature. Correspondingly, as the hydrogen bonding index increases, the solvent changes from poorly hydrogen bonding to strongly hydrogen bonding. Therefore, the most hydrophobic solvents appear in the lower left hand corner of the charts, and the most hydrophilic solvents appear in the upper right hand corner of the chart. Polymers are then tested for solubility in various solvents shown on the charts, and the regions of solubility determined and hence the solubility parameters can be defined for the polymers.
Floor polishes, contain polymers which have high glass transition temperatures because they must form hard surface films which have to stand up to abrasion and abuse. They also have high solubility parameter values because they need to be easily removable with basic soaps and water. In addition, many of these polymers must be made into salts and/or cross linked with di-functional metals in order to raise their effective glass transition temperatures. This also raises their solubility parameters. Those polymers used in floor polishes with their high glass transition temperatures and solubility parameters are not useful in the present invention. In fact, lower values are required for ease of application and film durability.
Polymers similar to those used in this instant invention can be found described in U.S. Pat. Nos. 4,172,122, 4,552,755, 4,816,256 and U.S. application Ser. No. 290,579, filed on Dec. 27, 1988. The polymers used herein, for this new furniture polish, are typically harder, and have higher T.sub.g values, than those described in these patents. The current polymers can contain more of the harder monomers for example methyl methacrylate.
U.S. Pat. No. 3,328,328 describes a water-insolubilized composition containing a styrene-ethyl acrylate-methyl acrylate copolymer and alkali metal aluminate in an emulsion floor wax. The styrene/ethyl acrylate/methacrylic acid polymer has a T.sub.g of 355.degree. K., and a .delta. of 9.7 (cal/cc).sup.178.
Canadian Patent Application Number 198282 (4-26-74) assigned to S. C. Johnson & Sons Inc, describes a floor polish and sealing composition containing an acrylic resin terpolymer of 55-60% methyl methacrylate, 10-15% methacrylic acid and 25-30% butyl acrylate, a polyethylene wax emulsion and water. The described polymers have T.sub.g 's from 333.degree.-338.degree. K. and .delta. of 11.5-11.6 (cal/cc).sup.1/2.